1. Field of the Invention
The present invention relates to an apparatus for inspecting electronic component insertion in a printed circuit board, and more particularly to an apparatus for inspecting electronic component insertion in a printed circuit board and the method therefor by inspecting a brightness change in clinching directions of component lead wires.
2. Prior Art
Automatic insertion of a component into a printed circuit board for an electronic product production has been attempted from the past, even though the automatic insertion is widely used nowadays. Automatic insertion procedures are performed in the order of (1) making up an electric circuit layout, (2) making up a circuit pattern to be printed on a board based on the electric circuit layout, (3) making up data of components to be inserted into the board according to the printed circuit pattern, (4) collecting information on insertion positions, insertion components, insertion directions, etc., by using the printed circuit pattern and converting the information into numeric control data for each equipment, (5) inputting the numeric control data into an automatic insertion equipment, supplying printed circuit board already made as mentioned above and components required to be automatically inserted for fitting into the printed circuit board, and (6) soldering the component-inserted printed circuit board by using an automatic soldering equipment for completion.
In the procedures as above for a finished printed circuit board, a procedure having a major effect all over the procedures is the one that inspects whether or not the components are inserted. During a series of procedures, unless correction is made to non-inserted or misinserted components before soldering, the uncorrected printed circuit board must be discarded, including the components. Further, the overall procedures for the printed circuit board become wasted.
Accordingly, it is imperative to discover any misinsertion of the components just after making a finished printed circuit board. However, in the past time, there was not a non-insertion inspection method, apart from that using the human eye. An inspection method using the human eye causes the inspection standard to vary depending on a worker's emotional state, work speed and time depend on worker's skill, obtaining a skilled worker is difficult, and a lot of time is required for a worker to become skilled.
In order to solve the problems as mentioned above, holes are detected by taking a picture of printed circuit board before inserting the components by means of a sight inspection equipment, the outer perimeters and the diameters of the holes are calculated to compare them to each other for determining whether the components are inserted into the holes, and maximum and minimum lengths are calculated from the center of each hole to the outer perimeter and determined to be a hole in case that the ratio lies in a criterion range.
In case that the clinched lead wires become adjacent to each other because the holes are made in an adjacent position, a picture of lead wires adjacent to each other is taken to obtain an image. The image is processed by an image processing procedure for an exact insertion inspection. However, a drawback exists in that an exact insertion inspection can not be obtained since adjacent lead wires are determined to be one lead wire.